package uk.ac.manchester.cs.owl.owlapi.turtle.parser;

/**
 * Describes the input token stream.
 */

public class Token implements java.io.Serializable {

    /**
     * The version identifier for this Serializable class.
     * Increment only if the <i>serialized</i> form of the
     * class changes.
     */
    private static final long serialVersionUID = 1L;

    /**
     * An integer that describes the kind of this token.  This numbering
     * system is determined by JavaCCParser, and a table of these numbers is
     * stored in the file ...Constants.java.
     */
    public int kind;

    /** The line number of the first character of this Token. */
    public int beginLine;
    /** The column number of the first character of this Token. */
    public int beginColumn;
    /** The line number of the last character of this Token. */
    public int endLine;
    /** The column number of the last character of this Token. */
    public int endColumn;

    /**
     * The string image of the token.
     */
    public String image;

    /**
     * A reference to the next regular (non-special) token from the input
     * stream.  If this is the last token from the input stream, or if the
     * token manager has not read tokens beyond this one, this field is
     * set to null.  This is true only if this token is also a regular
     * token.  Otherwise, see below for a description of the contents of
     * this field.
     */
    public Token next;

    /**
     * This field is used to access special tokens that occur prior to this
     * token, but after the immediately preceding regular (non-special) token.
     * If there are no such special tokens, this field is set to null.
     * When there are more than one such special token, this field refers
     * to the last of these special tokens, which in turn refers to the next
     * previous special token through its specialToken field, and so on
     * until the first special token (whose specialToken field is null).
     * The next fields of special tokens refer to other special tokens that
     * immediately follow it (without an intervening regular token).  If there
     * is no such token, this field is null.
     */
    public Token specialToken;

    /** An optional attribute value of the Token. Tokens which are not used as
     * syntactic sugar will often contain meaningful values that will be used
     * later on by the compiler or interpreter. This attribute value is often
     * different from the image. Any subclass of Token that actually wants to
     * return a non-null value can override this method as appropriate.
     * 
     * @return the value */
    public Object getValue() {
        return null;
    }

    /**
     * No-argument constructor
     */
    public Token() {}

    /** Constructs a new token for the specified Image.
     * 
     * @param kind */
    public Token(int kind)
    {
        this(kind, null);
    }

    /** Constructs a new token for the specified Image and Kind.
     * 
     * @param kind
     * @param image */
    public Token(int kind, String image)
    {
        this.kind = kind;
        this.image = image;
    }

    /**
     * Returns the image.
     */
    @Override
    public String toString()
    {
        return image;
    }

    /** Returns a new Token object, by default. However, if you want, you can
     * create and return subclass objects based on the value of ofKind. Simply
     * add the cases to the switch for all those special cases. For example, if
     * you have a subclass of Token called IDToken that you want to create if
     * ofKind is ID, simply add something like : case MyParserConstants.ID :
     * return new IDToken(ofKind, image); to the following switch statement.
     * Then you can cast matchedToken variable to the appropriate type and use
     * sit in your lexical actions.
     * 
     * @param ofKind
     * @param image
     * @return the new token */
    public static Token newToken(int ofKind, String image)
    {
        switch(ofKind)
        {
            default : return new Token(ofKind, image);
        }
    }

    /** @param ofKind
     * @return token of kind */
    public static Token newToken(int ofKind)
    {
        return newToken(ofKind, null);
    }

}